stalker

#!/usr/bin/env ruby
require "pathname"

class Stalker
  attr_reader :paths

  def initialize(script)
    @handlers = {}
    @paths = []
    instance_eval(script.read)  
  end

  def stalk(path, &block)
    Dir[path].each do |p|
      path = Pathname.new(p)
      add_handler(path, block) if path.file?
    end
  end
  
  def add_handler(path, block)
    if @handlers.key? path
      @handlers[path] << block  
    else
      @handlers[path] = [ block ]
      @paths << path
    end
  end 
  
  def handle(path)
    @handlers[path].each { |handler| handler.call(path) }
  end
end

class Engine
  def initialize(script_path)
    script = Pathname.new(script_path)
    if script.file?
      @stalker = Stalker.new(Pathname.new(script_path))
      init_file_sizes
    else
      puts "Attempt to load the script file from #{script_path}. File not found."
      exit
    end
  end

  def run
    loop do
      @sizes.each do |file, size|
        if file.size != size 
          @sizes[file] = file.size
          @stalker.handle(file) 
        end
      end
      sleep 1
    end
  end
  
  def init_file_sizes
    @sizes = Hash.new(0)  
    @stalker.paths.each do |path|  
      @sizes[path] = path.size
    end
  end
end

puts "Start watching..."
Engine.new(ARGV.first || "watchlist").run